A characteristic feature of the mammalian retina is that visual information is extracted and relayed to the brain in several parallel and funcitonally distinct pathways referred to as the W-, X- and Y- cell pathways. Anatomical studies suggest that Y-cells are alpha-cells, X-cells are beta-cells and W-cells are gamma-cells. However, specifying the morphology of physiologically identified ganglion cells is only an initial step in understanding the functional organization of these parallel pathways. It is also important to explain the physiology of ganglion cells in terms of synaptic connections within the retina and to specify the central projections of each functional cell type. Unfortunately, although several indirect approaches exist for addressing these issues, no direct method is presently available for identifying the morphology and microcircuitry of ganglion cells whose central projections are known. Our goal is to combine two techniques, namely, in vivo retrograde labeling of retinal ganglion cells with fluorescent latex microspheres with an in vitro retina-eyecup preparation for anatomical and physiological studies of retinal ganglion cells. Initially, this method will be used to examine the morphology and dendritic distribution of ganglion cells in the inner plexiform layer that have different central targets. Hopefully, these studies will establish the basis for future anatomical and physiological studies of isolated, identified ganglion cells growing in culture. This approach offers a way to examine ganglion cell types and the central connections that underlie the development and maintenance of parallel visual pathways and should enhance our knowledge of human vision.